1. Field of the Invention
The present invention relates generally to a hermetic compressor, and more particularly, to a discharge valve of a hermetic compressor which is installed in a cylinder head and discharges a compressed refrigerant.
2. Description of the Related Art
Generally, a hermetic compressor is employed in equipment using a refrigerant, such as an air conditioner, and a refrigerator, for compressing the refrigerant.
As shown in FIG. 1, a general conventional hermetic compressor comprises a stator 1, a rotor 2 rotating inside the stator 1, a crank shaft 3 revolving with the rotor 2, a piston 5 connected to the crank shaft 3. A connecting rod 4, reciprocates linearly with the revolution of the crankshaft 3. A cylinder 6 forms a compressive chamber 6B, together with the piston 5, and a valve assembly 7 assembled into a cylinder head 6A for controlling the discharge and a suction of the refrigerant.
The valve assembly 7 consists of an intake valve, which opens during an intake stroke when the piston 5 moves to the bottom dead center and closes during a discharge stroke when the piston moves to the top dead center, and a discharge valve, which opens during the discharge stroke and closes during the intake stroke.
Referring to FIG. 2, the discharge valve 10 includes a valve plate 11, a reed valve 13, a stopper 14, and a keeper 16.
The valve plate 11 has an intake hole 8 for refrigerant intake into the chamber 6B (FIG. 1) and a discharge hole 12 for discharging refrigerant. The discharging hole 12 is formed in a recess 11A of the discharge plate 11.
Within the recess 11A are consecutively piled on and installed in sequences the reed valve 13 for opening/closing the discharge hole 12, the stopper 14 for controlling the degree of opening of the reed valve 13, and the keeper 16 for preventing the reed valve 13 and the stopper 14 from separation from the discharge plate 11.
The operation of the conventional hermetic compressor comprising the same structure as that described above is explained hereafter.
When the rotor 2 rotates by the mutual operation of the rotor 2 and the stator 1, the crank shaft 3 assembled together with the rotor 2 revolves. When the crank shaft 3 rotates, the refrigerant is drawn into and discharged as the piston 5 reciprocates rectilinearly inside the cylinder 6 by the reciprocal action of the connecting rod 4 eccentrically assembled at the end of the crank shaft 3.
For the start of a discharge stroke, the piston 5 moves to the bottom dead center and inside the compressive chamber 6B forms a vacuum. Accordingly, the intake valve (not shown) of the intake hole 8 opens by the refrigerant pressure which displaces the valve toward the vacuum and the refrigerant flows into the compressive chamber 6B. At this point, the reed valve 13 (FIG. 2) keeps the discharge hole 12 closed. With the piston 5 at the bottom dead center, the piston 5 moves back to the top dead center and thereby the discharge stroke compresses the refrigerant and discharges it through the discharge hole 12 and into a discharge tube 9 (FIG. 1). During the discharge stroke, the intake valve closes off the intake hole 8 by means of the pressure of the compressed refrigerant whereby the compressed refrigerant is discharged through the discharge hole 12 by the same pressure pushing up the reed valve 13 and the stopper 14.
In addition, when the piston 5 reaches the top dead center, it begins its movement back again to the bottom dead center, the reed valve, which was moved up and open, falls down and closes the discharge hole 12 and continuous suction and discharge of the refrigerant proceed as the intake valve of the intake hole 8 opens.
Accordingly, the hermetic compressor continues the refrigerating cycle of refrigerant intake, compressing the refrigerant and discharging the compressed refrigerant in accordance with the above described process.
However, in the above discharge valve 10, in order for the refrigerant to be discharged during the discharge stroke the discharge hole 12 should be opened by the actions of lifting the reed valve 13 and the stopper 14. In other words, since the force produced by the discharge pressure of the refrigerant should be higher than the total closing force due to the elasticity of the reed valve 13 and the stopper 14 in order for the discharge hole 12 to remain open. Opening of discharge hole 12 allows the refrigerant to discharge, mere and a higher refrigerant pressure than the pressure required for operation of the pressurization of the refrigerant will be required in compressive chamber 6B. When the cylinder 6 is over pressurized, more power is needed to rotate the rotor 2, thereby resulting in the operation of the hermetic compressor in a less efficient state.
Additionally, it is also problematic in that the compressor makes loud noises due to the beating or impulse sounds made by the reed valve 13 hitting the top of the discharge hole 12 due to the elastic closing force of the reed valve 13 and the stopper 14 combination, and in the action of the piston 5 occurring at the time of the intake stroke.
The present invention has been made to overcome the above-mentioned problems of the prior art, and accordingly, it is an object of the present invention to provide a discharge valve for a hermetic compressor that is quiet and effective as a result of the cylinder not being over-pressurized by compressing and discharging the refrigerant against the weight of the valve itself during the discharge stroke.
Another object of the present invention is to provide a discharge apparatus of a hermetic compressor that is simple in shape, simple to process and assemble by being comprised of a small number of structural elements.
In order to achieve the above objects, according to the present invention a discharge valve of a hermetic compressor is installed in a cylinder head which opens and closes according to the reciprocal movement of a piston moving within the cylinder head, for discharging compressed refrigerant. The discharge valve of the hermetic compressor includes a valve plate disposed on the cylinder head of the hermetic compressor providing intake and discharge of refrigerant according to reciprocal movement of the piston. The discharge valve has a discharge hole formed therein through which refrigerant is discharged, a disc valve disposed above the discharge hole of the valve plate, being raised or lowered by the reciprocal movement of the piston, and a stopper disposed adjacent the disc valve and separated from the discharge hole, for guiding the raising and lowering of the disc valve and also for limiting the height to which the disc valve may be raised to a predetermined range. Alternatively, a hermetic compressor having a cylinder head and a piston for providing sequentially intake and discharge of a refrigerant during an intake/discharge cycle, adjacent to a discharge valve, the discharge valve may comprise a valve plate disposed on the cylinder head including a discharge hole formed therein for discharge of the refrigerant, a disc valve disposed adjacent the discharge hole of the valve plate, so as to cover the discharge hole during a portion of the intake/discharge cycle depending on the pressure developed within the cylinder head by the piston, and a stopper, adjacent to the disc valve and spaced from the discharge hole, including guides for guiding the orientation of the disc valve and a stopper portion for limiting to a predetermined range the reciprocal motion of the disc valve between the disc hole and the stopper portion.
Preferably, the stopper is connected to the valve plate with a space therebetween by a plurality of guiding pins that are standing upright around the discharge hole of the valve plate, to thereby guide the disc valve by point-contact between the disc valve and the guiding pins.
In another embodiment, the stopper is connected to the valve plate with a space therebetween due to supporting members extending downward from two ends of the stopper, for guiding the disc valve by line-contact of the supporting member and an edge of the disc valve. The stopper is connected to the valve plate with a space therebetween due to a supporting member extending downward from one end of the stopper, and has a plurality of guiding pins protruding from the other end of the stopper toward the valve plate for guiding the disc valve.
The stopper preferably comprises at least three guiding pins, one end of each guiding pin being connected to a circumference of the discharge hole of the valve plate in a vertical manner, while on the other end of each guiding pin is formed an extended end for limiting the height to which the disc valve may be raised.